Most meningitis is caused by the presence of bacterial or viral infections in the blood and problems with the permeability of the blood-brain barrier, resulting in the migration of bacterial, viral, fungal or tuberculosis infections from the blood to the meninges or brain parenchyma, causing inflammatory lesions in the meninges or brain parenchyma. First, bacterial meningitis is caused by a bacterial infection, and there are three types of bacterial meningitis, namely Haemophilus influenzae, Neisseria meningitidis and Streptococcus pneumoniae infections. Second, tuberculous meningitis is a non-suppurative inflammation of the meninges caused by Mycobacterium tuberculosis and accounts for about 6% of systemic tuberculosis. Third, viral meningitis, which is mainly meningitis caused by intestinal and respiratory viral infections such as coxsackievirus, hand, foot and mouth disease EV71 virus and herpes simplex virus. Fourth, other types include cryptococcal meningitis, cryptococcal meningitis can also be caused by cryptococcal infection, which can be found in pigeons, healthy people are not easily infected with fungal meningitis, but for HIV-infected people, it is easy to cause fungal infection because of immunodeficiency, viral and bacterial meningitis can be transmitted through direct contact with the nasopharyngeal secretions of patients.